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T White

Publications and source records attributed to T White.

210 records · Page 12Linked to original sources
PubMedDate not supplied

Attenuated nocturnal rise in pineal and serum melatonin in a genetically cardiomyopathic Syrian hamster with a deficient calcium pump.

Day and nighttime melatonin production in the pineal gland was compared in normal and cardiomyopathic (polydystrophic) adult male Syrian hamsters. These strains of hamsters were selected for comparison because the cardiomyopathetic hamster displays a deficient transmembrane Ca(2+)-pump in a number of tissues, and intracellular CA2+ concentrations ([Ca2+]i) play a central role in the nocturnal increase in pineal melatonin synthesis. Daytime levels of all constituents measured, i.e., pineal N-acetyltransferase (NAT) activity, pineal and serum melatonin levels, and pineal 5-hydroxytryptophan (5-HTP), serotonin, and 5-hydroxyindole acetic acid (5-HIAA) contents, were comparable in control and dystrophic hamsters. In contrast, the nighttime rises in pineal NAT activity and pineal and serum melatonin levels were significantly attenuated in the dystrophic hamsters. By comparison, the pineal contents of 5-HTP, serotonin, and 5-HIAA were essentially the same in both groups of hamsters with both pineal serotonin and 5-HIAA values exhibiting the usual nighttime drop. It is presumed that the alterations in nocturnal melatonin production in the pineal gland of the cardiomyopathic hamster may relate to a generalized deficiency in the Ca(2+)-pump in pinealocyte plasma membranes, which leads to unusually high [Ca2+]i, causing a depression of NAT activity; this leads to the commensurate decline in pineal and serum melatonin levels. Harderian gland NAT activity and melatonin levels were essentially similar in the two groups of animals, although NAT activity was slightly depressed in the dystrophic hamsters killed during the day. The reduced amounts of intrascapular brown fat in the cardiomyopathic hamster is speculated to be a result of the diminished amount of melatonin produced in these animals.

Animals↗
PubMedDate not supplied

Common data model for neuroscience data and data model exchange.

OBJECTIVE: Generalizing the data models underlying two prototype neurophysiology databases, the authors describe and propose the Common Data Model (CDM) as a framework for federating a broad spectrum of disparate neuroscience information resources. DESIGN: Each component of the CDM derives from one of five superclasses-data, site, method, model, and reference-or from relations defined between them. A hierarchic attribute-value scheme for metadata enables interoperability with variable tree depth to serve specific intra- or broad inter-domain queries. To mediate data exchange between disparate systems, the authors propose a set of XML-derived schema for describing not only data sets but data models. These include biophysical description markup language (BDML), which mediates interoperability between data resources by providing a meta-description for the CDM. RESULTS: The set of superclasses potentially spans data needs of contemporary neuroscience. Data elements abstracted from neurophysiology time series and histogram data represent data sets that differ in dimension and concordance. Site elements transcend neurons to describe subcellular compartments, circuits, regions, or slices; non-neuroanatomic sites include sequences to patients. Methods and models are highly domain-dependent. CONCLUSIONS: True federation of data resources requires explicit public description, in a metalanguage, of the contents, query methods, data formats, and data models of each data resource. Any data model that can be derived from the defined superclasses is potentially conformant and interoperability can be enabled by recognition of BDML-described compatibilities. Such metadescriptions can buffer technologic changes.

Animals↗
PubMedDate not supplied

The utility of postmortem lung for RNA studies; variability and correlation of the expression of surfactant proteins in human lung.

Postmortem human lung tissue was evaluated for its utility in studies of the mRNAs for the surfactant proteins. Data obtained from different analytical procedures indicated that surfactant protein mRNAs are quite stable in these tissues with a half-life of 10 to 12 h. These analyses revealed no major regional differences in the mRNA levels for the surfactant protein A (SP-A) and surfactant protein B (SP-B) although small differences were present in the levels for the surfactant protein C (SP-C). Analysis of adult surgical lung specimens indicated that there is greater individual variation in the mRNA levels for SP-A and SP-B compared to SP-C among individuals. Furthermore, in a given individual the level of SP-A mRNA correlated well with that of SP-B, whereas the level of SP-C mRNA did not correlate with either that of SP-A or SP-B.

Cadaver↗
PubMedDate not supplied

Implementation of recommended health maintenance activities in geriatric care.

To determine the extent to which health screening and preventive measures are actually documented in family practice, a random sample of 216 charts of established patients over 65 in seven practices was audited. Overall, a high rate of documentation (greater than 95%) was observed for blood pressure measurement. Intermediate rates of documentation (35% to 75%) were observed for oral cavity examination, smoking history, and skin examination. Low rates (less than 30%) were present for tetanus immunization, influenza immunization, stool occult blood testing, visual screening, hearing screening, mental status testing, social support description, and discussion of care preferences (living will). Several diagnoses for which screening was infrequently documented were recorded at rates approaching expected community prevalence figures, a finding that suggests widespread performance of informal or undocumented health screening in these practices. Recommended measures to increase the performance and documentation of preventive care include changes in the medical record, alterations in reimbursement, and delegation to nonphysician office staff.

Aged↗
PubMedDate not supplied

Nocturnal hypoxaemia and cor pulmonale in severe chronic lung disease.

The relation between daytime and nocturnal hypoxaemia on one hand and right ventricular failure (RVF) and hypertrophy (RVH) on the other was studied in 21 patients with severely reduced ventilatory capacity. RVH was assessed by myocardial scintigraphy, vector cardiography and echocardiography. Seven patients had suffered from acute RVF at least once. They had lower vital capacity and PaO2 and higher PaCO2 than patients without a history of RVF. They also had a more severe nocturnal hypoxaemia. They did not, however, have more severe RVH than patients without a history of RVF. Blood gases during daytime were not related to RVH. Oxygen saturation during sleep had a weak inverse relationship to RVH determined with scintigraphy, but not with the other methods. Nocturnal hypoxaemia was closely related to hypoxaemia and hypercapnia during daytime. A difference between daytime PaO2 and PaCO2 less than 2 kPa could with reasonable accuracy identify patients with nocturnal hypoxaemia.

Aged↗